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J Oral Maxillofac Surg69:623-637, 2011

Using a Clinical Protocol for OrthognathicSurgery and Assessing a 3-Dimensional

Virtual Approach: Current TherapyLuis A. Quevedo, DDS,* Jessica V. Ruiz, DDS,†

and Cristobal A. Quevedo, DDS‡

Oral and maxillofacial surgeons who perform orthognathic surgery face major changes in their practices, andthese challenges will increase in the near future, because the extraordinary advances in technology appliedto our profession are not only amazing but are becoming the standard of care as they promote improvedoutcomes for our patients. Orthognathic surgery is one of the favorite areas of practicing within the scope ofpractice of an oral and maxillofacial surgeon. Our own practice in orthognathic surgery has completed over1,000 surgeries of this type. Success is directly related to the consistency and capability of the surgical-orthodontic team to achieve predictable, stable results, and our hypothesis is that a successful result is directlyrelated to the way we take our records and perform diagnosis and treatment planning following basic generalprinciples. Now that we have the opportunity to plan and treat 3-dimensional (3D) problems with 3Dtechnology, we should enter into this new era with appropriate standards to ensure better results, instead ofsimply enjoying these new tools, which will clearly show not only us but everyone what we do when weperform orthognathic surgery. Appropriate principles need to be taken into account when implementing thisnew technology. In other words, new technology is welcome, but we do not have to reinvent the wheel. Thepurpose of this article is to review the current protocol that we use for orthognathic surgery and compare itwith published protocols that incorporate new 3D and virtual technology. This report also describes ourapproach to this new technology.© 2011 American Association of Oral and Maxillofacial Surgeons
J Oral Maxillofac Surg 69:623-637, 2011
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n the scientific literature, we have found manyrticles that describe the latest developments andpplications of computed tomography imaging ineneral,1-5 as well as the multiple applications anddvantages of cone beam computed tomographyCBCT) in particular.6-15 This imaging technologyacilitates many other related applications, such ashe generation of 3-dimensional (3D) models,rowth and craniofacial morphology studies, virtualrthodontic planning, and virtual surgical planning,mong others (Fig 1).16-34 We strongly recommend

*Full Professor, Oral and Maxillofacial Surgery, University of Chile,

Director of Surgical-Orthodontics Institute (ICOR), Santiago, Chile.

†Orthodontist, Private Practice, and partner of Surgical-Ortho-

dontics Institute (ICOR), Santiago, Chile.

‡Intern, Boston University Oral and Maxillofacial Surgery Depart-

ment, Boston, MA.

Address correspondence and reprint requests to Dr Quevedo:

ICOR Associated, Av Kennedy 5735, Torre Poniente Oficina 407

Las Condes, Santiago, Region Metropolitana, Chile; e-mail:

[email protected]

© 2011 American Association of Oral and Maxillofacial Surgeons

278-2391/11/6903-0006$36.00/0

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623

he article by De Vos et al,35 which systematicallyeviews CBCT in the oral and maxillofacial region,nd part I of the special series of articles thatppeared in the October 2009 issue of the Journal,ncluding the editorial by Assael.36-39 With theserticles in mind and being proactive users of mostf this technology in our orthognathic practice, weave found that, in many instances, new technol-gy can prevent people from having the right atti-ude regarding trying to use or obtain the “newhing” without proving of its effectiveness or vali-ation. The most important goal must be to alwayschieve the highest possible standards in patientare through validated treatment protocols.Our hypothesis is that is directly related to theay we take our records and perform diagnosis and

reatment planning following general basic princi-les.A strict protocol to take presurgical records in our

atients will give us consistent and predictable results,specially when a virtual approach will be used. Theseecords are based on oriented natural head positionONHP), the use of a true horizontal line as the onlyeference throughout the entire diagnostic and planning
rocess, the achievement of a temporomandibular joint
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624 CLINICAL PROTOCOL FOR ORTHOGNATHIC SURGERY

(TMJ)-centric relation, and the record of the true hingeaxis when the maxilla needs to be repositioned.

Materials and Methods

It is a common practice in orthognathic surgery to

FIGURE 1. Current imaging study of an orthognathic case, using C, D, E, Preoperative soft/hard tissue composite. F, Postoperativereoperative and postoperative superimposed 3D reconstructive im

uevedo, Ruiz, and Quevedo. Clinical Protocol for Orthognathic

develop a clinical protocol to study and plan patient

cases, and, usually, every surgical-orthodontic teamapplies its own modifications to the published proto-cols.40-43 In summary, these involve 3 steps. Step 1 isto establish the diagnosis. Doing so involves clinicaland imaging data gathering. In our practice we uselateral and frontal cephalometric radiographs and a

nd 3D software technology. A, B, Preoperative 3D reconstruction.ard tissue composite. G, Postoperative 3D reconstruction. H, I, J,.

y. J Oral Maxillofac Surg 2011.

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full-face cone beam scanner, based on which we per-

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QUEVEDO, RUIZ, AND QUEVEDO 625

form computerized frontal and lateral Ricketts andBjork-Jarabak analysis, along with other isolated ceph-alometric measurements.44,45 Another important diag-nostic tool for us is the use of semiadjustable articu-lator-mounted models, for which the proper use of aface bow is very critical. Step 2 is treatment planning,which includes cephalometric prediction tracings(both computerized and manual) and model surgery.Step 3 is transferring the final plan to the operatingfield, which we do through the final model surgeryand the fabrication of the intermediate and final sur-gical splints (surgical guides). This regular clinicalprotocol incorporates several critical steps, which areas follows.

STEP 1: DIAGNOSIS OF DENTOFACIAL DEFORMITY

A comprehensive diagnosis of a dentofacial defor-mity is the result of 2 main assessments. The firstassessment is a static routine evaluation of severaldiagnostic tools by use of routine techniques. In ourprotocol, these so-called static studies include facialand occlusal clinical photos, radiographs, and otherimaging studies; cephalometrics; and dental modelstudies. The second assessment is a dynamic evalua-tion of the patient, which includes an assessment ofthe capacity of the mandible to move in all directions,as well as an assessment of the TMJs, which movesynchronically depending on their functional andstructural health and depending on the organic (func-tional) relation of the patient’s teeth. We will reviewboth methods.

Static Diagnosis of Dentofacial DeformityIt is critically important that all of these studies be

consistent in terms of methods to be reliable. Unfor-tunately, inconsistency is a common error, and it hasbeen identified as the main cause of error in treatmentplanning and/or the implementation of the desiredplan to the operating room.46-58 We agree with theited literature, and we strive for consistency in ouratient records. Standardization and reproducibilityf the applied methods are key to achieving consis-ency, and to fulfill these 2 goals, we found sufficientvidence for use of the natural head positionNHP)59-67 and what has been called assisted naturalead position, or ONHP,68,69 as positions to recordur clinical photos. To identify the extension of therientation of the assistance of the patient’s ownHP, especially when we have a difficult case (a

everely asymmetric face or a patient reluctant toepeat a given position), we use a spirit-level guidelaced on the face bow44,45 (Fig 2A,B). This position-

ng allows us to assess our patients with respect to arue horizontal/vertical reference, which is a perma-ent common requirement for all of our records. Forhe imaging records, this assessment is achieved by
se of a true vertical reference, which appears on the b
ateral and frontal head radiographs by use of alumed chain. The patient is placed in ONHP with noar support, with soft tissues at rest, and in first toothontact. Since 2007, we started routinely workingith a cone beam scanner (CBCT) i-CAT apparatus

Imaging Sciences International, Hatfield, PA). Weuickly found that our usual, standardized way ofenerating images with a horizontal/vertical refer-nce was no longer possible because, among othereasons, this new technology needed a very still pa-ient in non-NHP.35,38 This limitation is still true for theajority of CBCT equipment, although the latest gener-

tions are working to improve this problem. Thereforee decided to extrapolate our method of transferring a

rue horizontal line to the panoramic radiograph44,70 toour protocol for orthognathic cases. We have been ableto obtain a reliable true horizontal reference in ourimaging studies by placing fiducial markers on the pa-tient’s skin to represent the true horizontal line, re-corded with the assistance of a horizontal line transfer-ring appliance (HOLTA) method.44,45 The accuracy ofhis method with a CBCT i-CAT machine was tested inn undergraduate thesis, currently in the process ofeing published.71 This method consists of using a faceow to establish the true horizontal reference on theatient’s skin with a set of 3 HOLTA devices, throughhich we make a mark on each side of the patient’sead, close to the tragus, and on the patient’s cheekFig 3A,B).

We appreciate the work by Xia et al38 and Gatenot al72,73 in this regard because they give an important

role to acquiring imaging data in NHP. They alsodescribe 2 different ways to obtain their virtual com-posite model in a true NHP, using a 3D laser surfacescanner or a digital gyroscope.38 However, we foundheir method to be expensive and complicated com-ared with ours, which is reliable, easy to use, inex-ensive, and consequently, much more viable (FigC,D). After this portion of the assessment, we couldse standard oriented imaging to perform cephalom-try. Whether we use manual or computer-generatedephalometry, and whichever analysis or software issed, it is important to obtain the structural diagnosisnd related characteristics using a standardized andeliable imaging protocol.

In the diagnosis of a dentofacial deformity, conven-ional cephalometrics with its related advantages,uch as the growth and visual treatment objectives oficketts et al,74 has been in practice for many years

and has been validated in numerous scientific publica-tions.75-82 At the point when we can conduct a true 3Dephalometric study, we should expect to have a muchetter understanding of dentofacial deformities, espe-ially the asymmetric or syndrome cases. In the litera-ure the term “3D cephalometric analysis” is confusing
ecause it has been used in many different ways.83-86

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We have been exploring these new tools, and weare confident in the enormous benefits these methodswill have for our patients. However, we do not thinkthat we need to create a new cephalometric analysisto use this method. We are accustomed to using theBjork method, modified by Jarabak, and Ricketts’ fron-tal and lateral analyses. We aim to have the same

FIGURE 2. ONHP with the guide of spirit levels placed on a face bhis NHP (ONHP). C, The assistance is being guided with spirit levebow nasion support or the maxillary fork with an inferior incisorleveling approach.

Quevedo, Ruiz, and Quevedo. Clinical Protocol for Orthognathic

angles and measurements in our 3D cephalogram s

using the tool of projecting these angles on the corre-sponding plane, as suggested by Swennen et al.85 How-ver, in our case those planes are not anatomically relatedut virtually (by mathematic algorithms) constructed auto-atically by the software at the time of imaging orientation

hrough the HOLTA references.Then, we strive to have clinical photos, imaging

, Asymmetric patient in his own NHP. B, Patient being assisted into, Frontal view of same assistance. It should be noted that the face

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consistent true horizontal reference, which allows usto study the “same patient” from both clinical andimaging records. We accomplish this by using ONHPand clinical recording of the true horizontal with theHOLTA method to consistently have it in the clinicalphotos and in the imaging we use.

The last of these diagnostic steps is to obtain a set

FIGURE 3. HOLTA system. A, Panoramic view of HOLTA device moC, Lateral view of patient’s horizontal reference painted on her skiLateral, frontal, and axial views of CBCT scan with HOLTA of sam


of articulated dental models, which is based on the

proper use of a face bow. As established by severalauthors,54,57,58 this step is another source of multiplepotential errors. We have to agree that, in a multi-stepprocedure, there are more opportunities to introducemistakes, and the sum of these errors could eventuallyproduce a poor treatment plan or a suboptimal finaloutcome. In performing the face bow transferring

on face bow. B, Lateral view of patient with HOLTA system in place.teral plain facial radiograph obtained with HOLTA marking. E-G,nt. H, I, Proper 3-dimensional orientation using HOLTA system.


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ulated models, we recognize that these instrumentsare semiadjustable and limited in the replication ofour patients. We should not expect these instru-ments to provide information other than what theyare designed to provide. With proper use, this is avery useful tool, and at present, it is essential toperform the treatment planning for orthognathicsurgery. We use model surgery and surgical wafers,which are fabricated in the laboratory via thesearticulated models,46,48-58 to transfer our plans to the

atient in the operating theater. Most of the new ap-roaches and the applications of new computer/virtualechnology have been directed to creating a virtual wafer,hich serves as a surgical splint generated by computer-

zed treatment planning.4,5,16,24,29,34,36-38 We believe thatthis technology represents the near future, and itspotential should depend more on us than the re-searchers or software companies developing a virtualsurgical wafer. We, the clinicians using this softwaredaily, are the real judges of the capabilities of the newachievements. From this perspective, what we askfrom both of these procedures, the conventional andvirtual type, is consistency, not only with respect tothe procedure itself but also with respect to the restof the records being used for diagnosis and treatmentplanning of the orthognathic patient. In other words,we require 1 permanent common reference for all ofour records. To this end, we use a true horizontal/vertical reference. Our clinical photos, radiographs,and cephalometrics, as well as the articulated dentalmodels for an ONHP patient, all use the same hori-zontal/vertical reference. Most of the semiadjustablearticulators, such as Panadent, Sam’s, Denar, Hanau,Whip Mix, and others,87-90 use what they claim to ben axio-orbitale plane, which is 2-dimensional (2D)nd anatomically arbitrary, to place their face bows.ost of these articulators use a pointer to place the

ace bow related to the orbitale cephalometric pointf the patient while the earring support is bilaterally

nserted. Others, like Panadent,89 assume that thisnterior vertical reference is 22 mm from the nasionupport of the face bow. When the face bow is se-ured on the patient’s head and the transfer fork isroperly locked to the patient’s maxillary arch, the

ace bow–fork unit is brought to the articulator forhe mounting procedure. Therefore these articulatorsse a reference that is quite different from a trueorizontal one, which we use to diagnose and planur patient cases. Whatever information we deriverom this procedure will not necessarily fully corre-pond to our patient’s dentoskeletal deformity. Forhis reason, we have begun using the same HOLTAethod to assist our patient’s NHP, and anytime theatient’s deformities mandate it, we fix the transfer

ork related to the position obtained in the face bow,
ollowing the frontal and lateral spirit levels44,45 (Fig
3A-E). With this method, we achieve consistency be-tween clinical and imaging records as well as cepha-lometrics and articulated dental models because theserecord and models are related to 1 true horizontal/vertical reference, which is used throughout our en-tire diagnostic study. For example, when we decideto perform superior and anterior repositioning of themaxilla by 5 or 6 mm, we are able to accomplish thispositioning correctly at surgery because the diagnosisand the treatment planning are consistent with thepatient’s vertical and sagittal deformity (Fig 1A,B).

Dynamic Diagnosis of Dentofacial DeformityDynamic in this case refers to function (ie, TMJ

participation in the studied dentofacial deformity).We believe that there are 2 different aspects in whichthe TMJ plays a key role in the diagnosis of a dento-facial deformity. One is in the case of a structuralproblem that relates to the deformity (vs malforma-tion, condylar hyperplasia, or progressive condylarresorption), and the other is in the case of a structur-ally healthy joint that has a condyle improperly seatedin its fossa. With the availability of CBCT and itsassociated software, the diagnosis of TMJ structuralproblems is much easier, and CBCT has become thestandard of care.35 The condyle/fossa relation is aconceptual matter, the discussion of which is beyondthe scope of this article. However, to validate ourprotocol we did an extensive review of the literature,which will be presented in the “Discussion” sectionof this article.

Our protocol for orthognathic surgery uses a full-coverage arch splint for the time the patient needs toachieve condylar seated position/centric relation(CSP/CR), to reveal the real malocclusion and its re-lated skeletal deformity (usually between 2 and 3months). Records are taken to obtain the real skeletalmaxillomandibular relation with no tooth contact, aswell as 2 wax techniques with an anterior hard stop,which has been proven to be a reliable technique.91-93

Then, this maxillomandibular relation wax recordingis used to obtain the dental cast in the articulator,where the face bow has placed the maxilla in itscorrect position and, according to the HOLTA level-ing system, to have the true horizontal as a reference.This procedure, as shown in Figure 4, allows us to beconsistent with what we have done in all of ourprevious static and dynamic records.

Once we have our patient in CSP/CR, we use thisopportunity to go one step forward in our protocol,and we perform a true hinge axis clinical recording inall of our orthognathic surgery patients. The need forusing a true mandibular hinge axis, specifically whenwe need to perform a vertical maxillary impaction orany skeletal maxillary movement resulting in a man-
dibular autorotation, has been studied in the past,


FIGURE 4. Face bow transfer protocol using spirit levels to fix maxillary fork record. A, Lateral view of patient at ONHP using spirit levels.B, Frontal view. C, Maxillary fork fixation to face bow being aligned with bilateral and frontal spirit levels. D, Posterior view of face bowrecording of maxilla with real canting of occlusal plane. E-G, Articulated dental model with proper 3D alignment and mounted according tothe true horizontal reference.

Quevedo, Ruiz, and Quevedo. Clinical Protocol for Orthognathic Surgery. J Oral Maxillofac Surg 2011.

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particularly in the orthodontics and prosthodonticsliterature.91,94-97 Using the Whip Mix face bow andrticulator, Teteruck and Lundeen95 found that 75.5%f the approximate hinge axes would fall within a-mm radius of the true hinge axis. The results of atudy by Wood and Korne96 led them to concludehat, given its practicality and reliability, the use of thestimated hinge axis is recommended in orthodon-ics. However, only the true hinge axis is recom-ended for the study of mandibular movements, for

iagnostic and definitive equilibration of casts, forxtensive restorative reconstruction, and for maxil-ary surgical movements resulting in autorotation ofhe mandible.96,97 In our protocol we clinically record

the true hinge axis using a Hinge Axis Locator (code85301; Almore International, Portland, OR). This pro-cedure takes approximately 25 minutes to performand is incorporated as part of a whole presurgicalrecords session appointment, which includes clinicalphotos, determination of the HOLTA fiducial markingfor clinical photos and radiography/CBCT imaging.The CSP/CR wax recording and face bow recordingare necessary for the dental model montage in thearticulator. The whole session takes approximately 1hour. Using the 3D scenario in our patients, we areexploring the idea of mathematically calculating thetrue hinge axis, using an extra scan of 2 silicone biteswith proper radiopaque markers taken from the semi-adjustable articulator, where the dental models arearticulated via the wax recording of CSP/CR and viathe horizontal/vertical reference. With this proce-dure, we strive to develop a skull-dental composite3D model (virtual articulator), allowing us to studydental and skeletal relations more precisely.

STEP 2: TREATMENT PLANNING

The second aspect to include in the protocol fororthognathic surgery is treatment planning. This plan-ning includes cephalometric prediction tracings (bothcomputerized and manual) and model surgery. The con-ventional 2D prediction tracing techniques have beenbroadly included in all of the main surgical textbooksdedicated to orthognathic surgery40-43 and in the ortho-ontics literature.74,98,99 Each surgeon uses his or her

own modifications of the original techniques and meth-ods.100-102 Like other methods, our own method hasbeen published.45,103 Furthermore, these 2D manualmethods were the basis for the digital scenario providedby computed tomography.1,2,20,21,104-106 In addition, dif-ferent companies have launched their own software,such as Quickceph, Dolphin, or Nemoceph.107-109 Thissoftware, among several other software programs, al-lows the clinicians to study and plan their cases on theirown computer screen. Our method was adopted by one
of these companies.110 p
Both manual/mechanical and digital/computer meth-ods have the same major problem of being 2D, and forthat reason, both systems have the same room for error.In our practice, we have used both methods and foundthe same results because we always adhered to princi-ples discussed in this article. These principles includethe following: using the ONHP; using 1 true horizontal/vertical reference in all records; properly studying den-tal malocclusion and skeletal deformities using a CSP/CRmaxilla-mandible relation and using the true hinge axis;taking images with the soft tissue at rest and with firsttooth contact; and calibrating the lateral radiograph witha computer, as well as matching it with the lateral softtissues taken from the facial photo.

Now, imaging techniques along with the scanner andassociated software technology are widely used, and the3D era started first with cephalometry.9,83,104,111,112 Inthis regard, we appreciate the atlas book of Swennen etal,85 which is a great piece of work. Subsequently, 3Dreatment planning was researched, and 3D virtual plan-ing is now a reality.16,17,20,37-39,113-116 In this evolutionf treatment planning for orthognathic surgery, we canecognize one major advantage, which represents areat paradigm shift. We shift from a 2D tools realityoward the use of a proper 3D scenario to plan 3Deformities. Now, when we are expecting a full 3D

maging tool, we should ask for the same principles weave followed in the 2D scenario, because despite its

nherent restrictions, they have been the base of predict-bility and consistency. Thus, whatever skeletal prob-em our patient has, we will be able not only to see it butlso to understand the differences between both sides ofhe patient’s face and plan the appropriate way to treatis or her deformity. Unfortunately, most of the soft-are we have seen in this 3D scenario reproduces the

ame problems as 2D analysis or 2D imaging techniques.he presence of these problems is particularly truehen 3D cephalometry is presented, such as the worky Olszewski et al,117,118 in which there are right- and

eft-side cephalometric landmarks. An average point issed to do the actual analysis, which is exactly what weo when using the 2D techniques. Therefore we willave to wait until we have a real full 3D scenario toork up our patients.The next step in treatment planning for the orthog-

athic surgery protocol is the model surgery. The firsttem for us to establish is that, in pursuing predictability,

e use the Erickson platform46 to continue having aorizontal/vertical true reference. In addition, we al-ays perform the maxillary surgery first, which can belanned more precisely than the mandible from thesual 2D prediction tracings, and we let the modelurgery tell us what we should do in the mandible. Asith the chin, we take what we had decided in therediction tracing and correlate the movement we ex-
ected to have with how much the same point moved

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in the anatomic model surgery. We adjust the final chinsurgery according to these findings.

Many authors have shown that, in this step, there ismuch room for error.73,119-122 The main reasons for thiserror are the restricted anatomic and functional replica-tions of the semiadjusted articulator, which causes adifficult and arbitrary transfer of the maxilla with a facebow that uses an axio-orbital plane as a reference. Theother cause for errors is the unrealistic replication of theskeletal anatomy with a plaster dental model, whichmeans that the surgeon cannot duplicate or identify thedirection or the amount of movement (in millimeters)that the different parts of the involved bony structureswill undergo at the time of surgery. Although this is true,in our practice, we use the spirit level in the face bow totransfer the maxilla using the true horizontal/verticalreference, as in all of our records. This method is con-sistent with the use of the Erickson platform,46,50 whichmaintains the horizontal/vertical plane as the standardreference. In doing this, we are able to be aware of thedirectional changes we are planning with our surgicalprocedures. The other way for us to achieve more pre-cision with our model surgery is to work with what wecall anatomic sets of models. To make these models, wereplicate in the plaster the exact vertical and horizontalposition of what we call key skeletal structures in ourtreatment planning. These key structures are the ante-rior nasal spine (ANS), as it correlates to the upper lipsupport, and the nasolabial angle. The next key struc-ture is the so-called chin point, because we should knowwhat needs to be done with the patient’s chin. Then,laterally, we measure and mark on our anatomic modela point that represents the inferior border of the man-dible at the site of sagittal split osteotomies bilaterally;thus we should be more aware of the movement of boththe proximal and distal segments and the type of gap oroverlapping that will be present during surgery at thesepoints. The method we use to replicate all these skeletalkey structures uses the Erickson platform to measure theanterior-posterior and vertical position of the upper in-cisor related to the ANS, as measured on the lateralcephalometric radiograph and its tracing, and then, wecut or remodel the plaster to place the ANS reference.We use the same procedure we used to anatomicallymark the chin point, using the lower incisor and theanterior end of the chin osteotomy line as the referencepoint, and for the bilateral body references, we used thefirst molars and the inferior border of the related man-dible. As in surgery, we use a modified version of the LeFort I step osteotomy, previously described by Epkerand Fish,43 and we use a reference point 35 mm abovehe canines and 25 mm above the first upper molars. Wery to avoid measuring any other markings or referenceoints (Fig 5). With this anatomic marking of the keytructures, we gain better knowledge of the skeletal
ovements that we will observe at the time of surgery.
e maintain the direction of the horizontal/vertical ref-rence in every step of this protocol, and the amount ofovement we want to occur in our patient is also better

pproximated with the described anatomic models.hus we take model surgery very seriously. For us, it ismatter of trust. We allow up to 0.25 mm of adjusted

ange of error.As with the model surgery, in the 3D scenario, we

ave been working on the segmentation of the osteot-mies to create a more realistic scenario when weove the osteotomized segments. We believe that, ife are not able to reproduce the exact relations of

he distal and proximal segments, we will end up withdifferent result at the time of surgery. Although thisony segment relation has major implications withegard to bilateral split ramus osteotomy, it is alsoery important for the Le Fort I osteotomy, especiallyhen we perform segmental mobilizations.Efforts to exactly replicate the human masticatory

ystem with a mechanical apparatus were long agobandoned by us. Even the most adjustable articulatorossible will never replicate our patient. We exploredvirtual articulator with its mechanical version using

tereolithography of parts of the skull, which fullyeplicates the maxilla, mandible, and TMJ anatomy-dimensionally. This approach can be used in a me-allic frame to better study the malocclusion and thedeal occlusal relations we need to reproduce as anal outcome in our patient. Of course, it is a matterf time for the technology to give us the pendingolutions. Then, we will not use any mechanical de-ices or plaster models because everything will beone virtually in some central office as a service of an

maging technology laboratory.Precise replication of the masticatory system is one

f the expected outcomes of the 3D era; however, were looking for simulation, not only replication orrediction, and that can only be achieved through aomputer-generated full anatomic model and a virtualrticulator. Given the technical problems that stillxist in replicating teeth and functional occlusion,38

currently, we still need to continue using plaster mod-els and a mechanical articulator to fabricate the sur-gical splints to transfer our treatment planning to ourpatient at the time of surgery.

STEP 3: TRANSFERRING FINAL PLAN TOOPERATING FIELD

Finally, the surgical splints—both intermediate andfinal—will need to be made. Those splints should bethe end result of the whole process, and they shouldcome easily. The same results should occur in the 3Dvirtual scenario. With the segmentation and definitionof tooth anatomy that we see in the near future withthe right technology, we could simulate much better
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precision. The surgical splints should be predictableand consistent with the desired result. The actualresult of our type of model surgery has good predict-ability, but because this method is just an improved2D method, this approach will never be exact.

A computer-generated surgical splint has not yetbeen proven to be fully reliable in complex double-jaw surgical cases.35-39,73,123,124 In our opinion, the

istakes among the different groups of researchersainly replicate the same problem we found with the

onventional 2D protocols.

Discussion

Technology, research or researchers, and dissemina-tion of new knowledge (scientific publications) are notto be blamed but are to be congratulated for this rapidrace for the latest application of various inventions. The

FIGURE 5. Anatomizing plaster dental model to better reproducetaken from the lateral radiograph using horizontal/vertical referenplaster model and stereo lithography model.


clinician is responsible for finding the best possible care t

available, which is hopefully based on evidence-basedmedical-dental practice. We just need to remember thatwhat is in the scientific literature and has not beenproven is not necessarily good or bad. Although evi-dence-based practices are recommended when avail-able, practices that are not evidence based are not nec-essarily bad or wrong, like some authors claim.125 Mostf the time, these practices just lack relevant properlyesigned scientific literature.We have always thought that diagnosis is essential for

verything that clinicians do. In 3D virtual technology,e have an enormous tool that allows us to more closely

eplicate the actual patient. Incorporating 3D cephalom-try is essential, but we think we still have much to doefore achieving the right perspective in using this newool. The 3D cephalometric analyses we have seen inhe most recent literature duplicate some of the prob-ems that we experienced for a long time with conven-

l key structure movement at model surgery. A, Measurements areUpper and lower anatomized model. C, D, Comparison between


skeletace. B,

ional 2D analysis. In the 3D cephalometric analysis of

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Swennen et al,85 measurements were calculated be-tween landmarks on 2D cephalograms.9 Treil et al126

developed a 3D cephalometric analysis based on a com-plicated reference frame constructed on 8 landmarksbelonging to the trigeminal system. In addition, thisanalysis does not propose the use of any sagittal plane.Bettega et al, cited by Olszewski et al,117 proposed anutomatic 3D CT cephalometric analysis based on aimplified version of Jean Delaire’s architectural andtructural 2D cephalometric analysis.100 The analysis

and software presented by Olszewski et al,117,118 wholso presented an original 3D cephalometric analysisased on a transformation of Delaire’s classical 2D ceph-lometric analysis, surprised us the most. Their conclu-ions were as follows: “We demonstrated that the three-imensional analysis gives the same results as two-imensional analysis using the same skull.” Thisonclusion is surprising because we would expect manyifferences between a 2D and a 3D cephalometric studynd to gain a much better understanding of the skulltructures with 3D analysis. If our understanding is notmproved with 3D analysis, we wonder why this

ethod should be used. Perhaps the data necessary toreate 3D cephalometry based on 2D cephalograms istill lacking. Swennen et al85 have suggested gatheringhese data through the Internet, because all of the dataould be easily collected, and multicenter studies shouldive us extensive access to valid information.As per the functional records and the appropriateay to establish the skeletal and dental deformity, weelieve in the diagnosis and the treatment planningrom TMJ centric relation, which has proved to be theost reliable maxillomandibular relation functionally.e have done an extensive review of the literature,

nd there are numerous authors who believe that aentric relation is the best relation in the TMJ forunctional stability.91,127-147 In addition, it is critical to

have a well-seated condyle for the diagnosis of themalocclusion because this position is considered tobe the most reliable and reproducible reference pointfor accurately recording the relation of the mandibleto the maxilla.92,127,129,131,137 Therefore a determina-tion of the seated condylar position (SCP/CR) is aprerequisite for the analysis of dental and skeletalrelations. Furthermore, for the correct diagnosis ofthe dentofacial deformity and treatment,44,45,148 webring our orthognathic patients into their TMJ centricrelation; this treatment has been part of our protocol forat least a decade.149 Our method of achieving thisCP/CR relation in our patients is also a matter of con-inuously reviewing the relevant literature. Many studiesave shown that the neuromusculature positions theandible to achieve maximal intercuspation, regardless

f the position of the condyles.94,150-157 Therefore thecclusion dictates condylar position. The resultant mus-
le function can be too dominant so that the acquired
andibular position will often be mistaken by the clini-ian for the seated condylar position. Therefore clinicalandibular manipulation, which many surgeons use to

xamine their patients, is unreliable in determining theeated condylar position because of the effects of theeuromusculature. Neuromuscular deprogramming ishe key to reproducibility.94,127,130,131,139,150-156,158-166

Therefore we were obligated to perform neuromus-cular deprogramming in all of our orthognathic surgerypatients, and the time involved in this presurgical prep-aration depends on the type of skeletal deformity, asshown in our studies.149 Splint therapy has been pro-ven effective in deprogramming the neuromuscula-ture.94,130,139,151-155,157,159,160,162,163

Technology promises to improve our treatmentoutcomes. Technology is developed to serve the cli-nicians who are using it and applying it. However,one should be cautious of turning to the latest tech-nologic development too quickly, without first obtain-ing a base of knowledge and understanding of whathas been proven. We should not serve technology, oruse our patients to do so, because that is not whatmedicine is about.

Our group is working to create a total virtual workingenvironment in orthognathic surgery. We call this envi-ronment SAIEMSE, from its name in Spanish (Sistema deApoyo Integral para el Estudio y Manejo de las alteracio-nes esqueletales y dentarias, estéticas y funcionales delSistema Estomatognático). In English, this translates to“Comprehensive Aids System for the Study and Manage-ment of the Skeletal, Dental, Aesthetic or FunctionalAbnormalities of the Gnathic System.” This environmentrepresents a combination of software applications,which work as a total assistant within a virtual environ-ment in which the surgeon or any other person followsthe software instructions to introduce the patient’s data,just like any of the current 2D computed cephalograms.The system includes a virtual articulator, which in factshould not be a mechanical device trying to replicateour patients’ functions but is our actual patient’s skull,joints, and teeth moving as we command. We are surethis is just the beginning of what we will have availableto work with until software capable of assemblingDICOM (Digital Imaging and Communications in Medi-cine) files, coming from CBCT, magnetic resonance im-aging, single photon emission computed tomography,ultrasound, and other sources, is developed. We areconfident in the technologies that will be available in thenear future, such as a full virtual patient to study and onwhich to do our workup to simulate our treatments. It isalso true that, whatever we will have available and de-cide to use, it must be based on principles that shouldnever change. In the SAIEMSE project the software per-forms the analysis and makes a problem list at every stepof the study (facial analysis, model analyses, imaging,
cephalometrics, and so on). The software will produce


a chart and checklist whenever necessary and obtain aworking diagnosis to enter for the next step, which istreatment planning. This includes treatment simulationsthat can be printed or displayed. This training scenariodepends on the user’s wishes to perform everything byherself or himself or in a centralized office, where some-one else will perform these tasks.

Orthognathic surgery, in conjunction with surgicalorthodontics, has been shown to be the best way totreat dentofacial deformities. When appropriately per-formed, it is predictable and provides consistently goodresults. To achieve these results, surgeons have exam-ined and practiced protocols for diagnosis and treatmentplanning and consider those at least as important as thesurgery itself. Predictability comes from consistent out-comes and makes these protocols reliable. Whether weare using the conventional manual and mechanical wayto study and plan our cases or we are using a digitalmethod, such as virtual 3D technology, we must per-form these methods correctly. For us, these protocolsmean that, for the static diagnosis part, we should haveour patient in ONHP to take our clinical set of photos ina repeatable standardized manner and to know up towhat angle to orient our patient’s NHP, whenever itshould be needed, using the spirit level. To achieveconsistency in all of our records, we should have aunique reference, which in our case is the true horizon-tal/vertical. For this reason, we transport this referenceto the patient’s skin through the HOLTA system, whichallows us not only to check the patient’s orientation inthe clinical setting but also to continue using the samereference with the fiducial markings. So, the patient isbrought to the radiography laboratory for either conven-tional frontal and lateral films or CBCT scan (or both). Atthe time when we perform our manual or digital ceph-alometric tracing, we use consistent radiographs andclinical photos that relate to each other. As soon as wediagnose our patient, we are ready to perform our treat-ment planning; we carry it out with the same truehorizontal reference that guides us in the movement wewant to transport to the model surgery. Therefore wewill plan the surgery manually or virtually to decide howmany millimeters we will move the jaw in a specificdirection. Here, we have to realize that we are planningfor a 3D problem in a 2D manner, and we will notexpect the prediction tracing to properly plan an asym-metric or syndrome case. Actually, to avoid misinterpre-tation from a 2D tool such as the lateral view we use, welet the model surgery, which is 3D, provide the exactsurgical specifications for us to perform in the mandible.The prediction tracing describes the surgery we willperform in the maxilla. However, even in the maxilla, ifwe have an asymmetric case, we cannot trust our lateraltracing. First, we should level the occlusal plane fromthe frontal view to determine the lateral impaction/
descending movements of the posterior maxilla and let
the model surgery tell us what to do with the mandible.The need to plan a 3D problem with a true 3D tool isone of the major motivations for developing 3D virtualplanning. Whatever we decide to do, we need to per-form this in the laboratory with the model surgery. Weare in a good position because we have specificallyanatomized sets of articulated models that have main-tained the same horizontal reference we use in clinical/radiographic records. Furthermore, the maxilla/mandi-ble relation has been captured by use of CSP/CRconsiderations and by use of the true hinge axis to rotatethe maxillary-mandible complex. In other words, all ofthe patient’s records are consistent among themselvesand with each patient’s real dentofacial deformity. Fi-nally, the fabrication and use of surgical splints—bothintermediate and final—just require practice. Thosesplints should be the end result of the whole process,and they should come easily. The only requirement forthis result to happen is that all of the previous steps aretaken following the same principles already mentioned.

The principles are the same for both the conven-tional manual/mechanical method and the new 3Dvirtual method. The goal is still to achieve the bestoutcome possible for optimal patient care.

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